Production shoe



Sept. 7, 1954 D. M. BEST ETAL PRODUCTION SHOE Fi led May 28, 1952 INVENTORS DAV/D M BEST ROBBINS M. CLAVPOOL ATTORNEY Patented Sept. 7, 1954FFIGE PRODUCTION SHOE David M. Best, Houston, andRobbins M. Claypool,Bellaire, Tex.

Application May 28, 1952, Serial No. 290,482 I 2 Claims. 1

This invention relates to production shoes and particularly to aproduction shoe to be secured at the lower end of a production tubing.

In an oil drilling operation a production shoe embodying this inventionis of special importance and isused when the well drilling operationreaches a stratum of oil bearing sand. It provides a form of drillingmeans for penetrating deeper into the oil bearing or pay sand and also astraining means to prevent solid matter from getting into the produtciontubing whereby it would be carried to the surface of the well and wouldcause damage to the valves of the pump if a pumping operation is ineffect or by fouling a pipe in a distributing system.

In addition to the foregoing it provides a means for cleaning andflushing out a well boring before actual oil production takes place.

It is an object of the invention to provide a production shoe designedfor attachment to the lower end of a production tubing.

Another object of the invention is to provide a production shoe havingan interiorly disposed strainer plug adapted to direct a stream of fluidto the bottom of a well boring to effect a cleanout operation.

Still another object of the invention is to provide a production shoehaving a strainer plug with drillings arranged therein adapted to impartturbulent action to a fluid passing therethrough.

A further object or this invention is to provide acomposite productionshoe that is made of two parts.

A still further and more specific object of the invention is to providea composite production shoe that comprises an outer cylindrical casingand an inner dome-like strainer member, said strainer member having anumber of downwardly directed holes drilled therein.

These and other objects will be apparent to those skilled in thisparticular art as set forth in the specification and defined in theappended claims when read in connection with the drawings in which Fig.1 shows a vertical side view, partly in section, of a production shoeillustrative of the invention.

Fig. 2 shows a fragmentary sectional view in perspective of a portion ofa modification of a strainer member having perforations extendingvertically therethrough at the top and almost Upon a vertical axis inthe side portions.

Fig. 3 shows a fragmentary section of another modification inperspective of the strainer 'memher showing perforations extendingthrough said strainer member spirally arranged to impart turbulence to afluid forced therethrough.

In the embodiment of the invention which is chosen for purposes ofillustration, in Fig. 1 is shown a production shoe l comprising a casingit having a strainer member it disposed therein. This casing Ill isprovided at its lower end with a series of serrated cutting members orteeth 52 which are adapted upon rotation to effect a drilling operationor to loosen material in the bottom of a well bore which is to beremoved by means of a flushing operation. Disposed within this casing isan annular horizontalshcub "der it on which the strainer member i i isadapted to be seated. Periphera-lly arranged about said casing are oneor more interiorly threaded holes adapted to receive set screws it forengaging a groove l6 located about the periphery of said strainer memberfor the purpose of connecting it fixedly with respect to said casing.The uppermost portion of said casing is provided with interiorlydisposed screw threads for securing it to the lower portion of aproduction tubing.

The strainer member as here illustrated is substantially dome-shaped andis provided with a series of perforations 2i] and 20A. The perforations2!], disposed at the upper portion of the strainer, may be straight, orotherwise stated, have their axes extending vertically and have adirection through the side wall of said tubing pointing towards thebottom thereof. The purpose and arrangement of these perforations is todirect all fluid towards the bottom of said strainer for flushingpurposes. This arrangement of perforations is illustrated in Fig. 1 ofthe drawing.

In a modified form the side walls of the strainer may be provided with'a plurality of spirally arranged perforations 28B extendingtherethrough and also directed towards the bottom of said casing, thisarrangement being made for the purpose of imparting turbulence to anyfluid forced therethrough for the purpose of flushing the interior ofthe well boring. The spirally ar ranged perforations'are illustratedinFig. 3.

This strainer is provided further with a conically flared base i ladapted to be seated on the shoulder [3 of the casing and the base isdisposed below the groove i6 and cooperates with the groove and setscrew arrangement to fixedly secure the strainer plug and casing to eachother. The inner annular shoulder 13 which lies in a horizontal plane asshown prevents downward 3 movement of the strainer with respect to thecasing. On the other hand the set screws l5 seated in the recess [6prevent upward movement. The shoulder [3, if desired, could be placedabove rather than below recess IS.

The production shoe, just described in some detail, functions in twoways. Before active production actually takes place, a suitable fluid,such as drilling fluid, may be forced under pressure down the productiontubing where it will pass through the perforations and 20A and act as acleansing agent to flush debris from within the well boring. The teethon the bottom of the shoe function very eificiently as a cutting means.As

the shoe is rotated, the teeth out into the sand or other debris andcause a certain amount of agitation which helps to remove theundesirable material in the bottom of the bore. When actual oilproduction is taking place, either through natural pressure within theoil well or through a pumping operation, the perforations 2D and 20Awill act as strainers to prevent solids from the interior of the wellboring from being carried up the production tubing.

This production shoe is made in two parts because, in the instance whereit is being used to a large extent for drilling purposes, the outercasing is the member subjected to the greatest wear and wouldundoubtedly wear out first. However,

that would be subject to the greatest amount of wear due to the abrasiveaction of matter being in place, and perforations of the casing havebeen made adjacent to the producing zone, production tubing is runinside the casing to some predetermined point above the bottom of thecased hole. This production tubing string of pipe has a round bull plugscrewed into the bottom 4 section, and the bottom section of this tubinghas numerous perforations (approximately i diameter drilled holes)staggered along a length of from 2 to 6 feet or more. The oil flow firstenters the cased hole from the producing zone through the perforationsin the casing and then enters the production tubing string through thenumerous perforations of the bottom section of tubing and thence on tothe top of the well, the flow of oil being actuated by either the gaspressure present in the producing formation or by artificial means suchas pumping or by gas lift equipment. Another method of completion em-vploys the setting of a casing screen which is set adjacent to theproducing formation thus eliminating the necessity of perforating thecasing as referred to above, but in either case the use of theproduction tubing is the same.

When the production shoe of the present invention is to be used on thebottom of the tubing string, the pull plug and the perforations in thetubing section described above are eliminated. Oil flows up through thebottom of the production shoe through the strainer plug to the top ofthe ground (or is pumped).

Employing the conventional bull plug and perforated tubing, when itbecomes necessary to wash the well to the bottom to remove sand or otherdebris which has either been brought into the well with the oilproduction or has not been cleaned out thoroughly after originaldrilling operations, the entire tubing string has to be pulled from thewell. After this the bull plug and perforated tubing section is removedand a bit of some type installed, and then the tubing is run back intothe hole and the debris is drilled, agitated, fluid circulated andremoved. Next, after this cleaning process has been completed, theentire tubing string is once again withdrawn from the well; the bit isremoved; and the perforated tubing section and bull plug once againinstalled and the tubing run back into the well again. Oil production isthen resumed.

However, with the production shoe of the present invention installed onthe bottom section of the tubing production string, when it becomesnecessary to clean and remove sand and other debris from the Wellbottom, the teeth on the bottom of the shoe serve the purpose of a bit,and actual drilling, milling, and agitation against the debris can beginimmediately. Since there is no perforated tubing section in the string,all of the fluid circulation is directed to the bottom of the tubingstring and the washing effect of the same is entirely directed out ofthe bottom. When all debris has been cut or milled up by the teeth onthe shoe and has been circulated out of the hole, then the well may beimmediately put back on production. It is to be noted that during theseoperations it was not necessary to remove the tubing string from theWell, but in the case of the conventional bull plug and perforatedtubing section two round trips with the production tubing string in andout of the well were required.

Pulling the tubing string in and out of the well is a long and expensiveoperation requiring much equipment and labor. The well equipped with thepresent production shoe can be cleaned out and put back on production ina matter of a few hours, while it is quite possible that one or moredays would be consumed when the conventional perforated tubing sectionand pull plug is employed. Also, wear and tear on tubing is eliminatedwhen the present production shoe is employed.

It is important to note that in the present construction the force orvelocity of the clean-out fluid is directed downwardly and concentratedat the location where it is most needed during drilling or clean-outoperations. The Work to be performed in clean-out operations isimmediately and directly below the bottom of the tubing, and inasmuch asfluid turbulence accomplishes much or more than mechanical agitationduring cleanout operations, it is essential that the full force andvolume of fluid be directed in its entirety to the very bottom of thetubing. This is believed to be the most important function of the hereindescribed production shoe. In addition to the force of the fluid andturbulence created thereby the milling teeth will effectively remove anydebris such as sand or heavy mud and shale from the bottom of the wellbore. This could not be accomplished by conventional practice whichrequires a perforated section that is ordinarily installed in the tubingstring at some distance from the bottom of the string.

If desired, a single strainer plug may have perforations extending alongvertical axes, angularly and spirally.

It is to be understood that the perforations 20, 20A, and 203 may bedrilled or otherwise formed in the strainer members. It is also possibleto use slots as distinguished from holes of cylindrical cross-sectionand here again the slots may extend on a straight axis or may be curvedas described in connection with the perforations.

The specific embodiment of the invention has been described in somedetails, but it is to be understood that changes and additions,substitutions and omissions may be made therein within the spirit of theinvention defined by the appended claims.

We claim:

1. A production shoe designed for use in conjunction with productiontubing, said shoe comprising an outer casing having a, strainer plugdisposed within the interior thereof, a cutting means provided at thelower edge of said casing, a shoulder extending around the interior ofsaid casing seating said strainer plug, a groove extending around theperiphery of said strainer plug, securing means disposed around theperiphery of said casing and extending therethrough and into said grooveto secure said strainer plug in fixed relation with said outer casing.

2. A production shoe designed for use in conjunction with productiontubing, said shoe comprising an outer casing having a strainer plugdisposed within the interior thereof, cutting means provided at thelower edge of said casing, a shoulder extending around the interior ofsaid casing seating said strainer plug, a plurality of perforationsextending vertically through said strainer member and adapted to directa stream of fiuid to the bottom thereof, and a second group ofperforations extending through said plug, said second group ofperforations being spirally arranged to impart turbulence to a fluidpassing therethrough.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 560,399 Durbrow May 19, 1896 940,733 Sands Nov. 23, 1909982,491 Heggem Jan. 24, 1911 1,804,819 Spencer et a1. May 12, 19311,869,352 Schneider et a1. July 26, 1932 2,192,945 Toney Mar. 12, 19402,491,796 Baume Dec. 20, 1949

